1. Field of the Invention
The present invention relates to a core around which a pressure-sensitive adhesive sheet is to be wound, a pressure-sensitive adhesive sheet roll, their production and a system for recycling the pressure-sensitive adhesive sheet roll.
2. Description of the Related Art
Wastes are by-produced in the manufacture of pressure-sensitive adhesive sheet rolls comprising a core and a pressure-sensitive adhesive sheet such as a tape, sheet or film wound around the core. In addition, the product pressure-sensitive adhesive sheets and cores become wastes after use. Such wastes must be treated. For example, a pressure-sensitive adhesive sheet comprising an overwide pressure-sensitive adhesive is wound and then cut to a specific width to yield a product pressure-sensitive adhesive sheet roll. In this case, both ends (edges) of the pressure-sensitive adhesive sheet roll become wastes. Portions of pressure-sensitive adhesive sheets which cannot be used as products also become wastes in switching of products or at early stages of operation until stable production starts.
Certain pressure-sensitive adhesive sheets are used for the surface protection of coatings typically against damage, blur or decoloring due to the attachment of suspended matter such as dust or collision of, for example, rain drops or fine stones during long-distance transit of coated automobiles and parts thereof by truck or ship. Such pressure-sensitive adhesive sheets are also used for the surface protection typically of stainless plates, aluminum plates, coated plates, resin plates and decorative sheets during storage, transit or press working. In the case of removable pressure-sensitive adhesive sheets such as masking sheets or pressure-sensitive adhesive sheets for semiconductors, cores become wastes when the pressure-sensitive adhesive sheets are applied and are then peeled off after use (after their object has been achieved) and become large amounts of wastes. Most wastes derived from such pressure-sensitive adhesive sheet rolls are incinerated, and only a part of them is recycled as a heat source (thermal recycling).
Waste disposal must be reduced and resources must be effectively utilized from the viewpoint of the environmental issues. Thus, materials must be recycled. However, such pressure-sensitive adhesive sheets each comprise a base sheet (base material) made of a variety of materials, a pressure-sensitive adhesive layer made of a variety of materials arranged on the base sheet, and a core made of paper or a plastic. These materials cannot be significantly recovered and reused separately. As a possible solution to this problem, Japanese Unexamined Patent Application Publication No. 07-80838 (claims and paragraph [0011]) discloses the reuse of edges of a pressure-sensitive adhesive sheet by pulverizing the edges, compressing or heat-compressing the pulverized article to yield a floor material or cushioning material. However, according to this technique, not all but only a part of the waste is reused, the reused molded article is not a pressure-sensitive adhesive sheet and is not recycled in exact meaning. Japanese Unexamined Patent Application Publication No. 2002-46944 (claims) discloses a recycling system for recovering and reusing a core of a wrap film. However, this publication fails to teach recovering and reusing a used film.
In Japan, Industrial Waste Wide-Area Recycle Designation Scheme has been established (see the website of Ministry of the Environment of Japan; URL: http://www.env.go.jp/recycle/waste/saisei/seido.html (in Japanese). This scheme is established to promote recovery and recycle of industrial wastes. This is a scheme in which the Minister of the Environment of Japan designates an organization which is proven to be capable of appropriately collect and recycle industrial wastes generated in wide area to thereby promote collection, transportation or treatment of industrial wastes. However, when such an organization intends to recover and recycle wastes of the pressure-sensitive adhesive sheet rolls according to this scheme, the wastes are difficult to recycle and remanufacture pressure-sensitive adhesive sheet rolls because of the complex structures of the pressure-sensitive adhesive sheet rolls. Thus, the resources are not effectively utilized.